Hello, I am trying to get those achievements for winning a battle against a player from a higher level.
I am using the VIP thing to search for enemy but the only I am able to find are bot commanders.
Is there any specific way to look for / search for other players within its level ?
thanks

simply put - No there isn't a feature that will allow you to look for Commander Bases from specified levels. VIP search is meant to assist you in finding non-PVP points of interest on the World Map. Please keep in mind that a search feature like that could be extremely exploitable by higher level commanders looking for Bases with more "fragile" defensive capabilities.